Historical record and sources of metals in core sediments from Maó Harbour, Minorca, Spain

Abstract

Maó (Minorca) is a narrow and semi-enclosed harbour impacted by historic urban and industrial metal pollution. We analyse and compare surficial and long-term sediment records along the Harbour to assess the sources and historical trends in pollution. Trace metal concentrations (Al, Ca, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sr and Zn) measured in sediments of Maó were of the same order of magnitude than those reported in other anthropogenically impacted areas of the Mediterranean Sea. Mercury was the only element that presented significantly higher concentrations in the harbour than other sites (up to 2 orders of magnitude higher). Although surficial concentrations of some metals (e.g. Hg, Pb, Cu and Zn) showed levels lower than those presented in the oldest sedimentary record, they showed concentrations above those recommended for acceptable sediment quality. Enrichment factors (EF) calculations support the anthropogenic origin of these metals in the Maó harbour; however, some variations can be attributed to natural fluctuations in the sediment deposition in the harbour.